Water Rise in Cappilary Tube - Where does the energy come from?

Click For Summary

Discussion Overview

The discussion centers around the phenomenon of water rising in a capillary tube and explores the source of energy responsible for this movement against gravity. Participants examine the roles of adhesion forces, internal energy, and chemical potential energy in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions who is doing the work to raise the water, suggesting that the internal energy of the molecules might be responsible, which could imply a decrease in temperature.
  • Another participant proposes that adhesion forces between water molecules and the tube walls are responsible for moving the water upward.
  • A similar viewpoint is reiterated, with an additional hypothesis that if adhesion forces are electrostatic, then the work might come from electrostatic energy.
  • Another participant agrees that adhesion forces, specifically hydrogen bonding, play a role and introduces the idea that potential energy is involved, noting that forming hydrogen bonds releases energy that contributes to gravitational potential energy as the water rises.

Areas of Agreement / Disagreement

Participants generally agree that adhesion forces are significant in the process, but there are differing views on the specific nature of the energy involved and its sources, leading to unresolved aspects of the discussion.

Contextual Notes

There are assumptions regarding the nature of adhesion forces and the relationship between chemical potential energy and gravitational potential energy that remain unexamined. The discussion does not resolve the implications of temperature changes or the exact mechanisms of energy transfer.

xCross
Messages
15
Reaction score
0
If a small tube (capillary tube) is dipped into the water, the water level rises. Which means someone is doing work on the water to rise it against gravity. My question is, who is doing this work?
My guess is the internal energy of the molecules is doing the work. That also means that temperature decreases slightly when rising the water. Is this the case?
 
Physics news on Phys.org
This is what i think:
Adhesion forces btn water molecules and the walls of the tube do the work of moving water up.
 
Sum said:
This is what i think:
Adhesion forces btn water molecules and the walls of the tube do the work of moving water up.

My guess:
If adhesion forces are kind of electrostatic forces, then the work is done by the electrostatic energy.
 
Yes, its the adhesion force (hydrogen bonding for water). In terms of energy, there is potential energy stored in the broken chemical bond. When the water and tube form a hydrogen bond, the chemical potential energy is released and becomes gravitational potential energy, i.e. the column of water rises. Forming chemical bonds releases potential energy (think explosives), and breaking bonds requires energy. To get a drop of water off a piece of glass, you have put energy in, such as by heating it or pulling it with a dropper.
 

Similar threads

  • · Replies 17 ·
Replies
17
Views
5K
  • · Replies 11 ·
Replies
11
Views
4K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 52 ·
2
Replies
52
Views
8K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
6
Views
6K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 13 ·
Replies
13
Views
5K
  • · Replies 10 ·
Replies
10
Views
2K
Replies
7
Views
2K